A. Field of the Invention
This invention relates to a composition for and a method of treating a porous media such as a subterranean formation wherein polymeric materials such as polyacrylamide, polyacrylic acid, and polysaccharides such as xanthan gum are removed from the porous media.
B. Description of the Prior Art
Aqueous solutions of polymers are commonly used in the recovery of hydrocarbons from a subterranean formation. For instance, in carrying out fracturing, acidizing, and polymerflooding operations, polymers, such as polyacrylamide, polyacrylic acid, and polysaccharides such as xanthan gum are commonly utilized. In addition, polymeric solutions are used to simulate field conditions on laboratory cores. It is often desirable to remove the polymer from the formation or laboratory core to increase the permeability thereof.
The term "permeability," as used herein, includes absolute or specific permeability and refers to a system where all three conditions for D'Arcy's Law are met and is usually defined as the permeability to one phase in a single phase system. This is the basic total rock permeability and is independent of the fluid present provided there is no reaction, physical or chemical, between the rock and the fluid which would alter the properties of either.
Various methods have been proposed for removing polymeric materials from a porous formation. For instance, U.S. Pat. No. 3,482,636 discloses a method of improving the permeability of a porous formation by injecting into the formation a composition comprising a hypohalite selected from the class consisting of water-soluble hypochlorites and hypobromites and an alkali metal hydroxide inhibitor sufficient to give an alkaline pH value of at least about 13.
U.S. Pat. No. 3,482,635 discloses the removal of polyacrylamide from a porous formation comprising contacting the formation with a basic aqueous solution consisting of mono and divalent metal salts.
U.S. Pat. No. 3,528,503 discloses the removal of organic materials from a geologic formation by injecting into the formation an aqueous solution of permanganic acid or a water soluble salt thereof followed by the injection of an aqueous solution of an acid having a ionization constant of at least 1.times.10.sup.-5.
U.S. Pat. No. 3,529,666 discloses the removal of organic materials from a geologic formation comprising injecting in sequence an aqueous solution of hydrogen peroxide, an alkali metal peroxide or mixtures thereof followed by the injection of an aqueous solution of an acid having an ionization constant of least 1.times.10.sup.-5.
U.S. Pat. No. 3,858,657 discloses the removal of polyacrylamide and its derivatives from a subterranean formation by contacting the formation with an aqueous polyamine solution.
The present invention provides a composition for and a method of solubilizing polymeric materials in a porous media in a one-stage treatment utilizing an aqueous composition which results in an increase in the permeability of the porous media.